Preheat the oven to 200ºF.
Using a box grater, coarsely grate the potatoes. Watch your fingers!
Place the potatoes in a colander lined with a clean kitchen towel or cheesecloth and let the potatoes sit for at least 15 minutes to release some of their liquid. Pick up the four corners of the towel or cloth and bring them together, then tightly wring the towel in the sink so that any extra liquid is squeezed from the potatoes.
Transfer the potatoes to a medium mixing bowl and add the grated onion, beaten eggs, flour, salt, pepper, and baking powder. Using a wooden spoon, stir until thoroughly combined.
In a large skillet over medium-high heat, add 1/4 cup of the oil to the pan. When the oil is hot, spoon the potato mixture, 2 tablespoons at a time, into the skillet to form individual cakes. You should be able to fit 4 or 5 latkes in the pan at a time. Using the back of a spoon, flatten each latke so that it resembles a pancake. Cook until golden brown, about 2 to 3 minutes. Using a metal spatula or tongs, carefully flip the latkes over, making sure to watch out for any splattering oil. Cook the latkes until the second side is golden brown, about 2 minutes longer.
Remove the latkes from the pan and set aside to drain on a paper towel-lined baking sheet. You can keep them warm in the heated oven while you cook the remaining latkes. Add more oil as needed and continue to fry the latkes in batches, making sure not to overcrowd the pan.
To serve, place a dollop of applesauce and/or sour cream in the center of each latke. Serve warm.
Yield: about 18 3-inch latkes